a) Field of the Invention
The present invention relates to apparatus and method for performing an automatic control over a velocity of an automotive vehicle in which the apparatus is mounted so as to maintain an inter-vehicle distance from the vehicle to another vehicle running ahead of the vehicle to follow up the other vehicle.
b) Description of the Related Art
A Japanese Patent Application First Publication (non-examined) No. Heisei 6-206469 published on Jul. 26, 1994 exemplifies a previously proposed automatic vehicular velocity control system.
In the previously proposed automatic vehicular velocity control system disclosed in the above-identified Japanese Patent Application First Publication, a radar unit is used to detect an inter-vehicle distance from the vehicle to a preceding vehicle which is running ahead of the vehicle. In a case where a variation rate of the inter-vehicle distance is equal to or below a distance variation threshold value, a variation rate of a magnitude of a reflected signal onto the radar unit is equal to or above a magnitude variation threshold value, and the vehicle is running on a curved road, the apparatus determines that the preceding vehicle has changed from the preceding vehicle running on the same traffic lane and transfers the vehicular velocity control mode from a preceding vehicle following up run mode into a mode of maintaining the vehicular velocity at the present vehicular velocity. The present vehicular velocity is a vehicular velocity when the above three conditions are established.